The country also has 402 kilometers (249 miles) of coastline on the Bight of Biafra, part of the Atlantic Ocean. The topography of Cameroon is varied, ranging from tropical rain forests in the south to mountainous highlands in some western central regions, and semi-arid savanna in the far north.
The Ionisphere bounces radio waves back to earth and regulates the amount of radiation that gets to the lower atmospheres. It all depends on the Sun's activity. The stratosphere is what actually protects us from the UV rays of the sun.
Medium wavelength radio waves are reflected from the ionosphere, a layer of charged particles in the upper atmosphere, so they can be used for long distance communication. Digital radio has better-quality reception as it uses digital signals and so does not have problems of noise and interference.